


Side Effects May Occur

by TheOriginalDL



Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Panty Poop, Panty Pooping, Pantypoop, Pantypooping, Pee, Soiling, Weird dreams, Wetting, bedmessing, magic laxative, peeing
Language: English
Status: Completed
Published: 2020-09-05
Updated: 2020-09-05
Packaged: 2021-03-06 14:40:56
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,475
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26310541
Author URL: https://archiveofourown.org/users/TheOriginalDL/pseuds/TheOriginalDL
Summary: In hope that she can improve her magic to better help her classmates and friends, Mercedes asks Manuela for a potion that can heighten magic potency. It seemed like a good idea at then time, though the concoction she had may have a few...side effects.
Comments: 1
Kudos: 15





	Side Effects May Occur

It was nighttime at Garreg Mach Monastery, and in one of the commoner rooms, Mercedes sat down on her bed while holding a bottle in her hands. A bottle filled with a strange, semi-transparent purple liquid that bubbled every few seconds. The substance appeared to be a concoction manufactured by dark magic, but it was not nearly something so sinister...at least, the pious young lady hoped as much.

Asking Manuela for a potion that could boost her magic seemed like a great idea at the time. There were few more knowledgeable about such topics than her, so why not ask the professor? However, when she went to get it, the older woman was just a little annebirated. Well, perhaps a little more than that. Absolutely smashed would probably describe her best, and after retreating into her room for a few short minutes, the potion she returned with looked nothing like how Mercedes was expecting. As though she had just made it in the little time she was back in her room.

Nonetheless, Mercedes trusted the professor, and made sure to heed her advice. Namely that she should drink it right before bed for maximum results. So here she was, already dressed in her nice, white night pants and shirt, mere minutes away from sleep and ready to get it over with. Still...she was hesitant. And not without reason.

“W-Well...Maybe I shouldn't...No!” Mercedes shook any doubts from her head before lifting the container up to her lips. “She wouldn't give me something if it was unsafe. It'll be fine.”

Hesitation free from her mind, the blond-haired young woman drank the potion and the taste was… Well, there wasn't very much taste at all. Whatever this had in it, it cancelled everything else out, though Mercedes couldn't say she minded. No taste was better than a bad taste, and it was leagues above what she had been expecting from it. Still, time would tell if it actually increased her magic prowess, but for now…

A yawn escaped her lips, and after setting the glass down onto her dresser, she snuffed out a lantern light illuminating the room and laid down in her bed. Getting underneath her blanket, Mercedes placed her head on her pillow and closed her eyes, quickly drifting off to sleep. She has to get a good rest, since she had classes the next day, and missing them because she overslept was certainly not something she could risk. Before long she was already losing herself to slumber, the last thing she felt being a small rumble in her stomach.

Eyes jolting wide open, Mercedes awoke to the sounds of classroom chatter. Wait, classroom chatter? Swiftly scanning the room around her, she found herself in the middle of class, already in her seat and surrounded by her classmates. Well, all her female classmates at least, including those from other houses. Was there some joint lecture today or something? If there was, why hadn't she heard about it? And to that end, why couldn't she remember coming to class?

Questions of all sorts swirled around in her head, but they, and the rest of the class for that matter, were silenced once the blue-haired professor walked up to the front. “Alright, quiet down. It's time to start the lecture.” Byleth never did enjoy wasting time. Right after that announcement, she began just as she said she would, giving a lecture on proper battle tactics and techniques. Nothing too unusual, and Mercedes tried her best to pay attention. ‘Tried’ being the keyword there.

A number of issues nagged at Mercedes that kept her from fully appreciating the lecture. How she had got here, why all the girls were here, the fact she hadn't heard about this lecture beforehand...and a pain right in her abdomen. A quickly growing one at that, despite the fact she had not felt anything before it suddenly struck.

Squirming in her seat, Mercedes attempted to ignore the feeling, but with each subsequent stomach rumbling she tensed up more and groaned. Needing to go to the bathroom in the middle of class was nothing strange, but she had never needed to go this bad before. Part of her wanted to ask to get up and leave, but...something was holding her back. Something in the back of her mind telling her not to go. To stay right here in class and push through the pain. 

So that's precisely what she did, listening to Byleth drone on and on about topics that Mercedes simply couldn't grasp. Mostly because every time she began to get invested, another pain made her tighten her rear end to stop anything from coming out. To distract herself and hopefully pass the time, the desperate girl looked around the classroom again...and noticed quite the odd thing. Namely, that she apparently was not the only one that needed to use the bathroom. Not by far.

In one corner of the room Hilda and Marianne sat next to each other, the former with her hands clutched firmly through her skirt and between her legs, and the latter looking quite stiff with a hand on her bottom. In another corner, Dorothea appeared to be holding up quite well at a glance, but a rapidly tapping foot and occasional quiet groan told a different story altogether. “What's...What's going on here…” She muttered to herself.

Class continued on for a while longer without interruption, though how much longer exactly, Mercedes was not sure. It could have been a half hour. It could have been six. Her perception of time was distorted by her potty needs, focus only on when the lecture would end, and a swift rush to the bathroom right after. By now she could practically feel it beginning to poke out, but she managed to hold it in. She could only wonder how the others were-

This thought was interrupted by a loud, rude noise sounding from one side of the room. One that was promptly accompanied by a soft pattering. Turning her attention towards it, Mercedes caught sight of Hilda’s skirt beginning to grow wet, alongside her seat, her socks, and the floor around her. Aside from a blush matching her hair on her cheeks, she hardly seemed fazed. Probably because she was preoccupied with a certain stinky student.

“Don't worry, Marianne. It's okay…” Hilda comforted the girl sitting next to her, who seemed mortified as she raised her butt of her seat and gave a few grunts. While Mercedes couldn't see what was happening exactly, she had a vivid picture of what was happening in the blue-haired girl’s panties.

“H-Hilda, it keeps...oh…” Marianne couldn't even finish her sentence, either because she was too ashamed to continue speaking, or because another wave of mushy mess began to fill her underwear. Probably both, given the lowered head and some more groans.

Suddenly realizing that she was staring at quite the shameful sight, Mercedes averted her gaze to give them some privacy. However, in doing so, she realized that no one else was doing the same...because no one was giving them any attention in the first place. Well, it was probably best that there was no one looking, but...why?

Surely the sounds would have tipped someone off, right? If not, then the smell certainly should have. But no one was giving it any thought besides her. Did they just not care, was there something more here?

“Ohhh…” Suddenly Mercedes’ attention was grabbed again, this time by Dorothea, who rose in her own seat. A steady trickle began to run down her legs from between her skirt, raising in volume and speed before it was practically a waterfall. That was not all, however, as the songstress promptly grunted and began to push something else out. This time, from her bottom. From the angle she was at as she pushed, the blond could easily see her panties sagging downwards from the filth inhabiting them, the light blue fabric stained considerably darker. Once done, she sighed in relief, sitting down and smushing the mess up against her butt with no cares any longer.

Just like before, no one questioned or mentioned this incident, as though they hardly noticed. Not even Ingrid, who did not seem the least bit distracted besides wrinkling her nose a little. This was all just too strange…

But suddenly, Mercedes was pulled back into her own problems. In the distraction caused by watching those other girls have their accidents, she had somehow forgotten about her own need to go. But in the time since she had last thought about it, the pressure had practically tripled. And there wasn't much time left. However…

Was the lecture still going on?! This was impossible! There was no way she would make it like this! “P-Professor!” Mercedes said while raising her hand, grabbing her teacher’s attention. “M-May I be excused to use the bathroom?”

“Mercedes, I'm in the middle of a lecture. Please-” Byleth began, before being abruptly cut off.

“It's an emergency!” Standing up out of her seat, Mercedes threw embarrassment to the wayside as she pleaded her case. “I-If I don't go now, I'm going to-Oh!” Squirming around as the pains hit her again, she placed both her hands on her rear, before begging again. “P-Please, I'm about to-”

Quickly Mercedes’ efforts turned futile. No matter how much she wanted to keep hold, her bowels decided they couldn't wait even a second longer. The moment her bottom began to open up and a huge mess started to pour out, she knew all hope was lost, and changed her intentions from holding on to getting the humiliation over with as quickly as she could.

“D-Don't look…” The pious pooper muttered in shame as her panties stretched, bulged, and sag from the mess she pushed into it. The long skirt hid it well, but the more perceptive students would likely notice the back of it being pushed out ever so slightly. Not that hiding it visually did her much good, since the crackling and squishes that came from soiling herself were obvious to all, not to mention the telling smells. All the while she kept her head lowered, eyes closed so that she could avoid looking at all the judging stares. Once the messing finally subsided, and her panties were full to the point of nearly spilling out, she decided that she finally had to face whatever the others said and thought. Lifting her head up, she took a deep breath, calmed herself down, opened her eyes, and saw the sunlight shining through her bedroom window.

What?

Eyes shooting wide open, Mercedes sat up in bed, covered in a cold sweat from the...nightmare? That would be the closest way to describe the experience, but that didn't seem quite right. Whatever it was, she was glad it was just a dream, and that meant that she hadn't…

A certain smell seemed to permeate the air around the bedroom. One that Mercedes was all too sensitive too right now. “Oh, no…” Sitting up in bed only gave credit to her suspicions, feeling a peculiar squish against her butt, which was almost certainly covered in brown muck right about now. If smell, feeling, and sound were already leading her to one conclusion, the last step would be to see it for her own eyes.

Lifting the sheets and getting out of bed, Mercedes stuck her butt out a little and looked over her shoulder, seeing exactly what she had expected. A brown, mushy stain clinging right against her rear, leaving nothing to the imagination. Perhaps wearing white pants to bed wasn't the best idea…

“Oh, this has never happened before!” Mercedes whined with a deep blush. “How could I have…” It was then that her eyes struck something sitting on a shelf. The empty glass container… There was no way it could have been the cause. Right? But… Well, Manuela did make it in a hurry. Perhaps it didn't improve her magic, and instead took something from her...namely, her continence, at least when she was asleep.

With the cause roughly figured out, Mercedes then promptly turned her attention back to her soiled rump. Cleaning up would be a hassle, and she would almost certainly need to throw these clothes away, but she had to do it. On that note, she had better get ready for class too, before-

The door slammed open behind her. “Mercie! You overslept!” The voice of a familiar, orange-haired girl called as she stepped inside. “Come on, you need to get ready before class….starts…”

Slowly turning her head back, Mercedes saw the widened eyes, wrinkled nose, and agape mouth of Annette staring right at her. Or, well, her butt to be more specific. “H-Hey there, Annie.” She greeted in an almost too casual manner with a nervous smile. “L-Listen, I can explain! S-See, I…”

Whatever Mercedes’ excuse was, she never got the chance to give it. Once Annette fully processed what she was seeing, she let out a gasp, and then… “I can't believe it! You too?”

“H-Huh?” Now it was Mercedes’ turn to be surprised, taking a moment to think through what Annette had just said. “W-Wait a minute, are you saying that…”

“Professor Byleth has been having accidents, and from the looks of things, you're having the same problems yourself!” Annette replied, revealing something much stranger than Mercedes could have predicted. “Phew! From the smell of things too.”

Watching as her best friend pinched her nose in an almost teasing fashion, Mercedes’ cheeks grew warm and crimson as she turned around to try and hide her mushy butt from her friend. Not that there was much use in that now. “A-Annie, I should probably get changed now, so if you would…”

Once the word ‘change’ came up, a light flickered in Annette’s eyes, one that did not put Mercedes at ease. “You're right! But we can't risk another accident like that, so come on! I know Professor Byleth has some diapers you can borrow!”

“D-Diapers?!” Mercedes exclaimed as her wrist was grabbed, already being dragged away by her younger, yet somehow stronger friend. With each forced step she took she felt the gross squishing between her legs, distracting her just long enough each time to not fight back. Before long she was pulled outside the room...and into the view of a great many other students, her brown bottom right on display for all of them. No matter how much she knew her friend was just trying to help, this was just a bit too much…!

“A-Annie, waaaaait!” The girl cried out, but such efforts were futile. Annette was only focused on helping her friend, and that's what she was going to do!

Even if it might ruin her reputation just a little...

**Author's Note:**

> This was fun to write! Mercedes is a personal favorite and I'm glad I wrote something with her. Might write a sequel to this if there's enough demand.


End file.
